This invention relates to a method and apparatus for inspecting steam traps provided in steam lines and/or condensate draining lines of an equipment operated using steam in order to drain condensate, and an management system for managing steam traps.
In steam lines and/or condensate draining lines of an equipment operated using steam in order to drain condensate, condensate may be produced by the heat exchange and/or heat release. If this condensate resides in the lines, it causes a reduction in operation efficiency. Accordingly, steam traps are generally provided in specified positions of the lines to drain the condensate.
The sealing performance of a steam trap may be deteriorated due to the deterioration of its valve portion with time, an operation defect and other causes. In such a case, steam in the steam lines leaks outside via the steam trap, leading to a wasteful steam loss. For example, in a large-size plant where several thousands to several ten thousands of steam traps are used, an amount of steam leaked through the steam traps is excessive, and an amount of a loss caused by the steam leakage cannot be ignored. Thus, the regular inspection of the steam traps is required. Conventionally, skilled workers have placed a diagnostic bar or a vibrometer against the traps, judged the steam leakage by experience based on the vibration of the valve portions caused by the steam leakage or the like, and performed a maintenance of the steam traps. However, the maintenance and inspection of the steam traps based on the experience of the skilled workers cannot secure a satisfactory efficiency and undesirably causes differences in the inspection result among skilled workers. Further, in large-size plants, not only the inspection of the steam traps, but also the totaling and analysis of the results and management of the steam traps require a lot of time and labor.
In view of these problems, there have been proposed some solutions. For example, U.S. Pat. No. 4,727,750 discloses a device for measuring steam leakage. Specifically, the device includes a vibration sensor for sensing a vibration of each steam trap, a temperature sensor for sensing a temperature of each steam trap, and a calculator for calculating steam leakage based on sensed vibration and temperature, thereby enabling automatic measurement of steam leakage in each steam trap.
Also, U.S. Pat. No. 4,788,849 discloses a system including a detector for measuring steam leakage in each steam trap, and a host computer for executing record and display of a summation of leakage in a plurality of steam traps, and totalization and analysis of leakage in terms of monetary cost or rejection rate.
However, such device and system as disclosed the above-mentioned United States patents do not execute any judgment as to whether or not the steam trap is of satisfactory quality. Such judgment is required to be made by maintenance personnel. Accordingly, there has been the problem in the aspect of precise inspection of steam traps. Specifically, the amount of leaked steam differs depending upon steam pressure used even if the steam traps are of the same type or have the same level of deterioration. Even if the amount of leaked steam is the same value, there are stream traps which should be judged to be normal and there are those which should be judged to be abnormal depending on the type thereof. Accordingly, the quality of a steam trap cannot be precisely judged if it is detected based on the steam leakage.
Further, it is preferable from the viewpoint of steam trap management to judge the quality of a steam trap during measurement by a portable detector. However, there have been proposed no system or device which makes it possible to judge the quality of a steam trap during measurement of the steam trap.